n = input("输入一个数")
m = input("输入一个数")
p = input("输入一个四则运算符")
# 判断输入的运算符是否为四则运算符后，进行计算
if p == "+":
    sum1 = n + m
elif p == "-":
    sum1 = n - m
elif p == "*":
    sum1 = n * m
elif p == "/":
    if m != 0:
        sum1 = n / m
    else:
        print("错误：除数不能为零！")

else:
    print("错误：不支持的运算符！")


print(sum1)
